Pre-Mesozoic evolution of Avalon terranes of southern New England

Skehan, James W.; Rast, N.

doi:10.1130/spe245-p13

Cited by 25 publications

(32 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1b). Skehan and Rast (1990) correlated the Cambrian Conanicut Group rocks of the Bulgarmarsh terrane with dark phyllite of the Cambrian-Ordovician Halifax Formation (now Group; ) of the Meguma terrane in Nova Scotia. Skehan and Rast (1990) suggested that the Bulgarmarsh terrane may have been thrust northwestward over the Pennsylvanian Narragansett Basin along the Beaverhead shear zone during the Alleghenian orogeny.…”

Section: Introductionmentioning

confidence: 97%

“…Skehan and Rast (1990) correlated the Cambrian Conanicut Group rocks of the Bulgarmarsh terrane with dark phyllite of the Cambrian-Ordovician Halifax Formation (now Group; ) of the Meguma terrane in Nova Scotia. Skehan and Rast (1990) suggested that the Bulgarmarsh terrane may have been thrust northwestward over the Pennsylvanian Narragansett Basin along the Beaverhead shear zone during the Alleghenian orogeny. However, based on its fossil assemblages, Landing (1996) correlated the Conanicut Group with lower to upper Cambrian stratigraphic units characteristic of Avalonia and discounted the existence of a separate Bulgarmarsh terrane.…”

Section: Introductionmentioning

confidence: 97%

“…In previous work on the Cambrian rocks in Beavertail State Park, three formations were recognized in the Conanicut Group, from oldest to youngest, the Jamestown, Fort Burnside and Dutch Island Harbor formations (Skehan et al 1981;Skehan and Rast 1990). The Jamestown Formation contains the Beavertail Point, Hull Cove, and Lionhead members, and the Fort Burnside Formation contains the Short Point and Taylor Point members; no members were recognized in the Dutch Island Harbor Formation.…”

Section: Cambrian Rocksmentioning

confidence: 99%

“…New England is composed of tectonic blocks, microcontinents, and/or terranes accreted to eastern Laurentia primarily during the Silurian-Devonian Salinic, Acadian, and Neoacadian orogenies, and the PennsylvanianPermian Alleghanian orogeny (O'Hara and Gromet 1985;Goldstein 1989;Skehan and Rast 1990;Wintsch et al 1992Wintsch et al , 2007Rast and Skehan 1993;Hepburn et al 1995;van Staal 2005;Hibbard et al 2006Hibbard et al , 2007. Over the last three decades, the number and extent of these terranes and the timing of their accretion and juxtaposition have been debated.…”

Section: Introductionmentioning

confidence: 99%

“…It is a composite terrane structurally subdivided into the penetratively deformed Hope Valley terrane and the less deformed Esmond-Dedham terrane, separated by the inferred Pennsylvanian Hope Valley shear zone in western Rhode Island (Fig. 1b) (O'Hara and Gromet 1985;Goldstein 1986Goldstein , 1989Skehan and Rast 1990;Gromet 1991;Walsh et al 2011). Rast and Skehan (1990) further subdivided the Esmond-Dedham terrane and defined a 'Bulgarmarsh terrane' located southeast of the Narragansett Basin and separated from the basin by the Beaverhead shear zone (Fig.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Alleghanian deformation of Cambrian metasedimentary rocks on Avalonia in south-central Rhode Island, USA

Carter¹,

Mosher²

2013

atgeol

View full text Add to dashboard Cite

Lower greenschist-facies metasedimentary rocks of the Middle Cambrian Conanicut Group occur in and around Beavertail State Park, Rhode Island. Detailed structural mapping (1:1000-scale) and petrology of these rocks indicate an early fold generation (F 1 ) and axial planar metamorphic foliation (S 1 ). F 1 is folded by a more prominent, E-verging, NNE-to NNW-trending, non-coaxial fold generation (F 2 ) and an associated pressure solution-enhanced crenulation cleavage (S 2 ). A third map-scale fold generation is inferred from NNE-trending broad folding of F 2 and S 2 . N-S extension resulted in boudins that deformed S 2 on a scale of 1-10 m, whereas late planar quartz veins indicate NW-SE extension. All structures are cross cut by faults striking N-to NE-and ENEto ESE that show dominantly normal motion with minor sinistral or dextral components. Kink bands associated with faulting trend NNE to ENE with WNW to NNW side up. The vertical Beaverhead shear zone juxtaposes the Cambrian rocks with Pennsylvanian rocks of the Narragansett Basin, and deflects S 2 in a dextral sense, consistent with motion recorded elsewhere.The Cambrian rocks record the same deformation and metamorphism as the adjacent Narragansett Basin rocks. No evidence was found for pre-Alleghanian deformation or for northwest-or north-directed thrusting and accretion of a Meguma-like terrane during the Alleghanian orogeny. If the Beaverhead shear zone was a preexisting terrane boundary within Avalonia, both the Cambrian and Pennsylvanian Narragansett Basin sediments were deposited after terrane accretion. AbStRACt RÉSUMÉDes roches profondes métasédimentaires du faciès des schistes verts, que l' on retrouve dans le groupe Conanicut du Cambrien moyen, sont présentes dans le Beavertail State Park, au Rhode Island, et dans les environs. Une cartographie structurale détaillée (à l' échelle 1:1 000) et la pétrologie de ces roches indiquent la formation précoce d'un pli (F 1 ) et une foliation métamorphique (S 1 ) de plan axial. Le F 1 est causé par la formation d'un pli (F 2 ) non coaxial plus dominant, à vergence est et d' orientation NNE-NNO ainsi que par une schistosité de crénulation (S 2 ) amplifiée en raison d'une dissolution par pression connexe. La formation d'un troisième pli à l' échelle cartographique est provoquée par un vaste plissement du F 2 et de la S 2 d' orientation NNE. Une extension N-S a produit des boudins qui déforment la S 2 sur l' échelle de 1 à 10 m, tandis que des veines de quartz planes formées ultérieurement indiquent une extension NO-SE. Toutes les structures sont traversées par des failles orientées N-NE et ENE-ESE montrant un mouvement normal dominant accompagné de composantes senestres et dextres peu importantes. Les bandes froissées associées à ces failles sont orientées NNE-ENE et présentent une tangente verticale ONO-NNO. Dans la zone de cisaillement verticale de Beaverhead, les roches du Cambrien sont juxtaposées aux roches de la Pennsylvanie du bassin Narragansett, et la S 2 dévie en un mouvement dextre, ce qui concorde...

show abstract

Section: Introductionmentioning

confidence: 97%